Electric lamp with lamp-cap-type base connector



Feb. 11, 1964 3,121,185

ELECTRIC LAMP WITH LAMP-CAP-TYPE BASE CONNECTOR H. J. H. POELS ETAL Filed Jan. 13, 1961 INVENTOR HENDRIKUS J.H.POEL5. HERMANUS J.P.FLOR|E.

BY M a FIG. 2

United States Patent 3,121,155 ELECTREC LAN? LAMP-QAP-TYPE CQNNETGE Hendriirus Eohannes riubertns Eoels and Johannes Petrus Floris, both oi Ein' hoyen, Netherlands, assign-tars to North Pullips Company, Inc, New York, NZL, a corpermnn oi flelaware Filed lien. 13, 19-61, Ser. No. $2,49 Claims priority, application Netherlands Feb. 13, 19% 3 Claims. ((3. 313-313) This invention relates to electric incandescent lamps provided with plug pins for an operating voltage higher than 100 volts and having a low wattage, wherein the plug pins me secured in the base of a lamp cap made of insulating material. A lamp according to the invention is characterized in that, while the bulb is secured to the cap solely by means of current-supply wires emerging from the bulb and connected to the plug pins, the bulb in the direction of its length is substantially surrounded by the lamp cap, the supporting wires inside the bulb being proportioned so that their free ends rem-ate from the pinch are located inside the space bounded by the lamp cap, and at least one flexible spacer being provided between the outer side of the bulb and the inner side of the lamp cap.

Lamps of this kind are used in rooms, for example, to obtain a limited local illumination. They are inserted into plug sockets locally available. As a rule, the disadvantage inherent in the use or" such lamps is that they are readily damaged due to their very arrangement in plug sockets. In addition, conventional plug-socket lamps formed as incandescent lamps involve the disadvantage that, if the bulb of a lamp positioned in a plug socket is damaged, the live supporting wires of the lamps are freely accessible and may thus give rise to accidents. This disadvantage might be obviated by making the lamp cap surround the bulb over a comparatively great length, thus reducing the chance of the bulb being damaged. It, in addition, the supporting wires inside the bulb would be proportioned so that their free ends remote from the pinch are located within the space bounded by the lamp cap, the advantage is obtained that, in case of breakage of the bulb, the freely accessible supporting wires are protected from direct contact, at least to a certain e tent, namely as reckoned from the sides of the lamp, by means of the cap still available. in order slightly to support the bulb in its lateral direction and to prevent the pieces of wire between the rear side of the bulb and the ends of the plug pins adjacent the bulb from being accessible from the front or" the lamp, it is necessary for the inner side of the lamp cap to surround the outer side of the bulb comparatively tightly. if no special steps are taken, it is found that during the use of such lamps, probably due to the difference between the coefficients of expansion of the material of the bulb and that of the cap, crack in the bulb occurs at a premature stage, so that a lamp thus constructed is not sufficiently reliable in operation. By taking in a lamp according to the invention also the step of arranging at least one flexible spacer between the outer side of the bulb and the inner side of the cap, the advantage is obtained that, during the operation of the lamp, the bulb now supported sufiiciently can also freely expand to a sutlicient extent without breakage occurring.

if in one advantageous embodiment of the incandescent lamp according to the invention, the flexible spacers are formed by one or more sleeves of metal sheet profiled in the transverse direction of the lamp, the further advantage is obtained that a reasonable ventilation occurs between the outer side of the bulb and the inner side of the cap. As a result thereof, during the operation of the lamp, the temperature of the lamp cap, by l. cans of which 3,l2l,l85 Patented Feb. 11, 1954 the lamp is handled by the user, is several tens of degrees Celsius lower than in the absence of such spacers.

If reference is made to a lamp of low wattage, a lamp is concerned having a wattage usually less than 20 watts and more particularly less than 10 watts.

In order that the invention may be readily carried into efiect, it will now be described in detail, by way of example with reference to the accompanying diagrammatic drawing, in which:

FIGURE 1 shows one embodiment of a lamp according to the invention, the cap of which is shown in longitudinal section, so that the bulb present therein and the structure of the spacer can also be seen;

FIGURE 2 is a longitudinal view of the lamp and FIG 3 is a plan view thereof.

In the embodiment shown, the lamp comprises a bulb ll of a more or less conical shape, into which a stem 2 is sealed. A filament of 6 watts for an operating voltage of 220 volts is stretched on support wires 3 and iof the ste.. 2 in a zigzag manner with the aid of supporting wires. A pinch 6 of the lamp contains in the usual manner an exhaust tube 7 through which the bulb is evacuated.

The bulb l is secured to a lamp cap it solely by means of current-supply wires 8 and 9 projecting therefrom.

The cap i comprises a substantially cylindrical portion 11 and a base 12, in which base two hollow plug pins 13 and is are flanged in position. The ends of the current-supply wires 8 and 9 are passed through the hollow plug pins 13 and i4 and soldered to the lower ends thereof with the aid oi amounts of solder 15' and 16.

As can be seen fr rn FIGURE 1, the bulb 1 is surrounded by the cylindrical portion ll of the cap it} substantially throughout its length. Consequently, the bulb is sufficiently protected from damage. If, unexpectedly, the bulb 1 would still be damaged, which in practice is possible in the embodiment shown only by breakage of the front 17 of the bulb, the damaged lamp, if it is still in a plug socket, does not in practice cause any danger, since the free ends P and Q of the pole wires 3 and 4 are located inside the space surrounded by the lamp cap =16.

From the foregoing it appears that the bulb 1 is secured to the lamp cap it solely by means of the comparatively slack conductors t3 and 9. This implies that the bulb 1 requires additional support in the cap it If the internal diame er of the cylindrical portion 11 of the cap R has too small a tolerance relative to the outer diameter of the bulb l, the danger previously referred to arises that upon the expansion of the bulb which occurs during the use of the lamp, the bulb contacts with the inner side or" the lamp cap it which might result in premature breakage of the bulb 1. In order to obviate this disadvantage, a sleeve 18 of metal sheet, more particularly of aluminum, which serves as a spacer, is arranged in this embodiment in the interspace between the outer side of the bulb 1 and the inner side of the cylindrical portion 11 of the lamp cap it). As can be seen more particularly from FIGURE 3, the sleeve 18 is profded transver ely to the direction of length of the lamp. it is thus ensured that the bulb 1, although supported, can freely expand to the desired extent. in addition, the presence of the sleeve-like body 1-3 is found highly to enhance the ventilation in the space between the inner side of tie lamp cap it and the outer side of the bulb 1. Also the presence or" the sleeve-shaped body prevents any contact with the conductors present in the space of the cap between the rear side of the bulb and the side of their entrance into the plug pins.

What is claimed is:

1. An electric incandescent lamp provided with plug pins having an operating voltage in excess of .100 volts and a relatively low wattage comprising a bulb having a pinch, a lamp cap of insulating materia surrounding said bulb for the greater part of said len'eth but spaced therefrom, said plug pins being secured in the base of sai lamp cap, current sugply Wires from said bulb being connected to said plug pins creating the sol connection between said bulb and said lamp cap, at least one flexible spacer arranged between the outer side of the bulb and the inner surface or said lamp cap, and supporting Wires in sm'd bulb their free ends remote from said pinch in the space bounded by the inner surface of said larnp cap.

2. An electric incandescent lamp provided with plug pins havi g an operating voltage in excess of 10%- volts and a relatively low wattage comprising a bulb having a pinch, a lamp cap of insulating material surrounding said 15 bulb for the greater part of from, said plug pins being said length but spaced theresecured in the base of said a lamp cap, current supply Wires from sai bulb being connected to said plug pins creating the sole connection between said bulb and said lamp ca at least one flexible spacer of a corrugated metal sheet which is profiled in a direction substantially transverse to the longitudinal axis of said lamp, and supporting Wires in said bulb having their free ends remote from said pinch in the space bounded by the inner surface or said lamp cap.

3. An electric incandescent lamp as claimed in claim 2 said flexible spacer is constituted of aluminum.

References Qited in the tile of this patent UNITED STATES PATENTS 1,977,195 W'ood Oct. 16, 1934 2,366,216 Roberts v Ian. 2, 1945 2,627,04 Lamb fan. 27, 1953 

1. AN ELECTRIC INCANDESCENT LAMP PROVIDED WITH PLUG PINS HAVING AN OPERATING VOLTAGE IN EXCESS OF 100 VOLTS AND A RELATIVELY LOW WATTAGE COMPRISING A BULB HAVING A PINCH, A LAMP CAP OF INSULATING MATERIAL SURROUNDING SAID BULB FOR THE GREATER PART OF SAID LENGTH BUT SPACED THEREFROM, SAID PLUG PINS BEING SECURED IN THE BASE OF SAID LAMP CAP, CURRENT SUPPLY WIRES FROM SAID BULB BEING CONNECTED TO SAID PLUG PINS CREATING THE SOLE CONNECTION BETWEEN SAID BULB AND SAID LAMP CAP, AT LEAST ONE FLEXIBLE SPACER ARRANGED BETWEEN THE OUTER SIDE OF THE BULB AND THE INNER SURFACE OF SAID LAMP CAP, AND SUPPORTING WIRES IN SAID BULB HAVING THEIR FREE ENDS REMOTE FROM SAID PINCH IN THE SPACE BOUNDED BY THE INNER SURFACE OF SAID LAMP CAP. 